Lead-acid storage batteries comprise a number of positive plates and negative plates assembled as elements in a cell. There may be one or more cells in each battery. The battery plates comprise an open metallic grid of cast lead alloy to which is added a filling of lead salts, principally lead oxides, lead sulfates and some free lead. The filling, or active material, is added to the grid in the form of a water suspension or soft paste. After pasting, the plate is allowed to set for a day or more during which time the soft paste hardens.
Inevitably in the battery manufacturing process there are defective or damaged finished dry plates or elements which must be scrapped. It is, of course, desirable to reclaim as much of the scrap material as possible in order to bottom manufacturing costs.
One current method for processing defective or damaged plates or elements for scrap reclaimation comprises placing the plates or elements in a melt-down kettle having a temperature about the melting point of lead. Approximately fifty percent of the grid metal or approximately 20 percent of the entire plate or element weight can be recovered as metallic lead in this melt-down process. The remaining fifty percent of grid metal together with the non-metallic components of the plates or elements are collected as dross in the melt-down process which must be further processed by an expensive smelting process for further metallic lead recovery.
The smelting process yields about 85 percent metallic lead from the dross with approximately 12 percent of the entire weight of the original scrap not recovered by these combined processes, i.e. melt-down and smelting.
In addition to the value of the non-recovered portions of the original scrap, the smelting operation costs the battery manufacturer about 50 percent of the entire value of the original plates or elements. It can thus be seen that a substantial savings can be obtained by avoiding the expensive smelting process.
Accordingly, an object of the present invention is to provide a simple, reliable and inexpensive process whereby scrap battery plates or elements can be reclaimed without the necessity of melting down and smelting the scrap battery plates as has been required heretofore.
For purposes of this disclosure, scrap battery plates are defined as any cured or non-cured, formed or unformed, wet or dry lead-acid battery plates scrapped for any reason, whether as individual plates or as completed elements or groups.